bpf: Check link_create.flags parameter for multi_uprobe

The link_create.flags are currently not used for multi-uprobes, so return
-EINVAL if it is set, same as for other attach APIs.

We allow target_fd to have an arbitrary value for multi-uprobe, though,
as there are existing users (libbpf) relying on this.

Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link")
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250407035752.1108927-2-chen.dylane@linux.dev

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index ec19942321e6d2ba4319ee2a62fbc7f725dc0ef8..0f5906f43d7cac102040225bf0916906c3b2bd88 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3379,6 +3379,9 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
        if (sizeof(u64) != sizeof(void *))
                return -EOPNOTSUPP;
 
+       if (attr->link_create.flags)
+               return -EINVAL;
+
        if (!is_uprobe_multi(prog))
                return -EINVAL;